This project seeks to develop new statistical techniques for problems in human development and to apply existing techniques to those problems in novel ways. In the past year, work focused on applications of statistical techniques to study a disease of childhood, attention-deficit/hyperactivity disorder (ADHD) and two neurological diseases of aging, amyotrophic lateral sclerosis (ALS) and Parkinson's disease. For ADHD, we are carrying out a case-control study in a local school district. We have recently published a description of our method for identifying cases in a field study as well as pilot results. We have also examined the prevalence of medication use for ADHD among elementary school children as assessed by parental report. Our surprising finding is that the prevalence of medication use, about 7%, exceeds the often stated prevalence of the disease, namely, 3-5%. For ALS, based on a case-control study that we conducted, we examined blood and bone lead levels as risk factors for the disease. We found that blood lead levels were more closely associated with disease than bone lead levels, contrary to the view that bone lead, as indicative of long-term exposures, should be the better indicator of risk. The planning and preliminary work of the Parkinson's disease study is complete and field data collection is now underway.